Drive device

ABSTRACT

[Object] To provide a drive device capable of increasing the drive precision of a movable member for generating power and capable of suppressing the generation of abraded particles. 
     [Solving Means] A fluid machine ( 100 ) according to this embodiment has a structure in which a connecting rod as a movable member of a pump unit ( 20 ) is not connected to a circling shaft ( 13 ) of a motor unit ( 10 ) via a bearing but fixed to the circling shaft ( 13 ). In other words, the connection structure between the circling shaft ( 13 ) and the connecting rod is a structure using no bearings, and the integration, that is, the rigidity, of the circling shaft ( 13 ) and the connecting rod can be increased, which can increase the drive precision of the connecting rod. Further, since there are no sliding portions between the circling shaft ( 13 ) and the connecting rod, the generation of abraded particles can be suppressed and the reliability of the fluid machine ( 100 ) can be increased.

TECHNICAL FIELD

The present invention relates to a drive device that is used as a fluid machine etc. such as a pump and a compression machine and generates power by using a driving force of a drive source.

BACKGROUND ART

A fluid machine such as a pump and a compression machine includes a mechanism to convert a rotational movement into a linear movement, for example, and produces a pump action or a fluid compressing action by using the linear movement.

In a dry vacuum pump described in Patent Document 1, a valve plate is opened and closed by the drive of a piston connected to a crank driven by a motor, thus performing exhaust and intake of gas (see, for example, FIG. 1 and description on FIG. 1 in Patent Document 1).

In an oscillating piston vacuum pump described as related art in Patent Document 2, an outer rotor is provided in a cylinder, and an eccentric rotating shaft of an inner rotor is driven by a motor. Accordingly, the inner rotor revolves about the rotating shaft while sliding on the outer rotor. In this process of the revolution, a vane is oscillated in a vertical direction while oscillating its neck, and air is introduced into a cylinder chamber via an intake passage provided to the vane and exhausted via an outlet (see, for example, paragraphs [0003] and [0004] and FIGS. 10 to 13 of the specification of Patent Document 2).

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-522426.

Patent Document 2: Unexamined Patent Application Publication No. HEI 6-108985.

SUMMARY OF INVENTION Problem to be Solved by the Invention

In the dry vacuum pump described in Patent Document 1, a piston rod is generally connected to a crank via a bearing, though not described therein. Therefore, the drive precision of the piston rod is reduced by a backlash of the bearing. In addition, heat (heated gas) may flow in from an intake passage. In this case, a bearing with high heat resistance has to be used, which increases costs.

In the oscillating piston vacuum pump described in Patent Document 2, the inner rotor and the outer rotor slide on each other, and therefore abraded particles are generated from both the members even if a lubricating material is used. Since there is a fear that a pump unit or a sealed portion may be damaged due to the generation of abraded particles, the reliability of the device is reduced.

In the dry vacuum pump of Patent Document 1 above, in the case where the bearing is not provided between the piston rod and the crank, the piston rod and the crank shaft slide on each other. Therefore, the same problem as the above-mentioned problem of Patent Document 2 is caused in this case as well.

In view of the circumstances as described above, it is an object of the present invention to provide a drive device capable of increasing the drive precision of a movable member for generating power and capable of suppressing the generation of abraded particles.

Means for Solving the Problem

To achieve the object described above, according to an embodiment, there is provided a drive device including a rotating shaft, a circling shaft, and a movable member.

The circling shaft is provided to be eccentric with respect to an axial center of the rotating shaft.

The movable member is a member that is fixed to the circling shaft and generates power by using a circling movement of the circling shaft that circles by a rotation of the rotating shaft.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view showing a fluid machine as a drive device according to a first embodiment of the present invention.

FIG. 2 is a view of a rotating shaft viewed in an axial direction.

FIG. 3 is a schematic cross-sectional view showing a main part of a pump unit including a movable member according to an embodiment in a direction of a rotating shaft of the motor unit.

FIG. 4 is a view showing a main part of a pump unit according to another embodiment of the present invention.

FIG. 5 is a view showing a main part of a pump unit according to still another embodiment of the present invention.

FIG. 6 is a view showing a main part of a pump unit according to still another embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing a fluid machine as a drive device according to a second embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

According to an embodiment, there is provided a drive device including a rotating shaft, a circling shaft, and a movable member.

The circling shaft is provided to be eccentric with respect to an axial center of the rotating shaft.

The movable member is a member that is fixed to the circling shaft and generates power by using a circling movement of the circling shaft that circles by a rotation of the rotating shaft.

In this embodiment, the movable member has a structure not being connected to the circling shaft via the bearing but being fixed to the circling shaft. In other words, the connection structure between the circling shaft and the movable member is a structure using no bearings, and the integration, that is, the rigidity, of the circling shaft and the movable member can be increased, which can increase the drive precision of the movable member. Further, since there are no sliding portions between the circling shaft and the movable member, the generation of abraded particles can be suppressed and the reliability of the drive device can be increased.

The drive device may further include a bearing that is provided within the rotating shaft and rotatably supports the circling shaft. With such a structure, the circling shaft is rotatable with respect to the rotating shaft (rotatable about its axis) in conjunction with the rotation of the rotating shaft. Accordingly, the circling shaft is rotatable about its axis in accordance with the movement of the movable member even if the movable member is fixed to the circling shaft. Therefore, it is possible to convert the circling movement of the circling shaft into a movement of the movable member.

The drive device may further include a diaphragm mechanism that is driven by the movable member and gives power to a fluid. In this case, the movable member is a connecting rod connected to the diaphragm mechanism.

The drive device may further include a piston head that is driven by the movable member and gives power to a fluid. In this case, the movable member is a piston rod connected to the piston head.

The drive device may further include a casing including an inlet of a fluid, an outlet, and an operating chamber that communicates with the inlet and the outlet and is provided with the movable member therein. In this case, the drive device further includes a vane that partitions the operating chamber into an intake side and an exhaust side of the fluid together with the movable member in accordance with a movement of the movable member within the operating chamber. In other words, the drive device is a vane pump. As the vane pump, for example, there are an oscillating piston pump and a cam pump. In the case of the oscillating piston pump, the movable member and the vane are formed to integrally move.

In the case of the cam pump, both a form in which a circling shaft is provided to be rotatable about its axis and a form in which the circling shaft is provided to regulate rotation about its axis can achieve conversion of the circling movement of the circling shaft into a movement of a rotor.

The circling shaft and the movable member may be a member formed by integral molding. Accordingly, the rigidity of the circling shaft and the movable member is increased, which increases the drive precision of the circling shaft and the movable member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment

FIG. 1 is a schematic cross-sectional view showing a fluid machine as a drive device according to a first embodiment of the present invention.

This fluid machine 100 includes a motor unit 10 and a pump unit 20 driven by the motor unit 10.

The motor unit 10 includes a rotor 11, a stator 12 arranged on the circumference of the rotor 11, a circling shaft 13 provided in the rotor 11, and a casing 5 that houses the rotor 11 and the stator 12.

The casing 5 includes a cylindrical main body 1 and a cover 2 mounted to an opening portion at one end (left end in FIG. 1) of the main body 1. The stator 12 includes a stator core 9 and a coil 8 and is housed in a stator housing portion 1 a provided in the main body 1 of the casing 5. The rotor 11 includes a rotating shaft 6 and a rotor core 7 provided on the circumference of the rotating shaft 6.

The rotating shaft 6 is rotatably supported by a bearing 14 attached to the main body 1 of the casing 5. FIG. 2 is a view of the rotating shaft 6 viewed in an axial direction. A through-hole 6 a is formed at a position that is eccentric with respect to an axial center of the rotating shaft 6. A bearing 15 that rotatably supports the circling shaft 13 is provided in the through hole 6 a. With such a structure, the circling shaft 13 is rotatable with respect to the rotating shaft 6, that is, rotatable about its axis.

The pump unit 20 to be described later is connected to an opening portion at the other end (right end in FIG. 1) of the main body 1 of the casing 5. An output end 13 a of the circling shaft 13 is connected to the pump unit 20, and a circling movement of the circling shaft 13 causes the pump unit 20 to generate power. Specifically, as will be described later, the circling shaft 13 is fixed to a movable member. The movable member is provided to the pump unit 20 and moves to generate power by using the circling movement of the circling shaft 13.

In the motor unit 10 structured as described above, when the rotating shaft 6 is rotated by an electromagnetic interaction between the stator 12 and the rotor 11, due to the rotation, the circling shaft 13 circles (revolves) about the axial center (Y-axis direction) of the rotating shaft 6.

(Description on Diaphragm Pump)

FIG. 3 is a schematic cross-sectional view showing a main part of the pump unit 20 including a movable member according to an embodiment in a direction of a rotating shaft of the motor unit 10.

This pump unit 20 shows a diaphragm pump (for example, vacuum pump). In a diaphragm pump 201, a diaphragm 27 is attached within a casing 51. Within the casing 51, a pressure chamber 25 is formed by the diaphragm 27. The pressure chamber 25 communicates with an area outside the casing 51 via an inlet (gas intake port) 23 and an outlet (gas exhaust port) 24 that are provided to the casing 51. In addition, the inlet 23 and the outlet 24 are provided with an inlet valve 21 and an outlet valve 22, respectively, to cause gas to flow in one direction. In the outside of the casing 51, the inlet 23 and the outlet 24 are connected with pipes and the like (not shown) that form part of a gas circulation channel.

It should be noted that the casing 51 of the pump unit 20 may be formed integrally with the casing 5 of the motor unit 10, or the casing 51 and the casing 5 may be formed to be continuous as an integrated member (for example, integrally molded product).

One end of a connecting rod 28 is rotatably connected to the diaphragm 27 via a connecting shaft 29. To the other end of the connecting rod 28, the output end 13 a of the circling shaft 13 that extends from the motor unit 10 is fixed. The circling shaft 13 and the connecting rod 28 are fixed to each other with a fixture such as a bolt (not shown).

The concept of fixing includes a form in which the circling shaft 13 and the connecting rod 28 are formed to be continuous as an integrated member. Further, the above-mentioned concept of fixing also includes coupling.

As described above, the circling shaft 13 is in a free state in its rotation direction. Thus, the circling shaft 13 can rotate about its axis so as to follow the movement of the connecting rod 28 when the circling shaft 13 circles. Accordingly, the connecting rod 28 converts a circling movement of the circling shaft 13 into a linear movement for driving the diaphragm 27. Accordingly, the volume of the pressure chamber 25 is changed and along with the change in volume, the intake and exhaust of gas via the inlet 23 and the outlet 24 are alternately performed.

As described above, the fluid machine 100 according to this embodiment has a structure in which the connecting rod 28 is not connected to the circling shaft 13 via the bearing but fixed to the circling shaft 13. In other words, the connection structure between the circling shaft 13 and the connecting rod 28 is a structure using no bearings, and the integration, that is, the rigidity, of the circling shaft 13 and the connecting rod 28 can be increased, which can increase the drive precision of the connecting rod 28. Further, since there are no sliding portions between the circling shaft 13 and the connecting rod 28, the generation of abraded particles can be suppressed and the reliability of the fluid machine 100 can be increased.

In addition, since there are no bearings and sliding portions, a lubricating material for such portions is unnecessary, maintenance is unnecessary, and the structure of the portions can be simplified.

Additionally, in such a diaphragm pump 201, the diaphragm 27 separates the pressure chamber 25 and an area 26 in which the connecting rod 28 is arranged from each other to be capable of being hermetically sealed, which is also effective in the case where a fluid is liquid.

(Description on Piston Pump)

FIG. 4 is a view showing a main part of the pump unit 20 according to another embodiment of the present invention. In the following description, members, functions, and the like that are the same as those included in the motor unit 10 and the pump unit 20 (diaphragm pump 201) according to the embodiment shown in FIGS. 1 to 3 will be simply described or description thereof will be omitted, and differences will mainly be described.

The pump unit 20 is a piston pump. A piston pump 202 includes a piston head 37 provided within a casing 52 and a connecting rod 38 rotatably connected to the piston head 37 via a connecting shaft 29. Similar to the above description, the output end 13 a of the circling shaft 13 of the motor unit 10 is fixed to an end portion of the connecting rod 38. In other words, there are no bearings and sliding portions between the connecting rod 38 and the circling shaft 13. A pressure chamber 35 formed by the piston head 37 communicates with an area outside the casing 52 via the inlet 23 and the outlet 24.

It should be noted that the piston head 37 has a cylindrical shape, for example, and is equipped with a seal ring (not shown) on an outer peripheral surface thereof.

As described above, the same effect as that of the diaphragm pump 201 can be obtained also by a fluid machine used as the piston pump 202. Further, this embodiment is also effective in the case where a fluid is liquid.

(Description on Oscillating Piston Pump)

FIG. 5 is a view showing a main part of the pump unit 20 according to still another embodiment of the present invention. The pump unit 20 shows an oscillating piston pump. The oscillating piston pump is one kind of vane pump.

An oscillating piston pump 203 includes a casing 53 that forms an inlet chamber 45 and an operating chamber 46 having a cylindrical shape. The inlet chamber 45 communicates with an area outside the casing 53 via an inlet 43.

A movable member 42 provided within the casing 53 includes a vane portion 42 a and a cylindrical rotor portion 42 b. The vane portion 42 a forms a flow path 42 c of gas. The cylindrical rotor portion 42 b is formed integrally with the vane portion 42 a and arranged within the operating chamber 46. It should be noted that the rotor portion 42 b may be fixed to the vane portion 42 a with components or the like. To the rotor portion 42 b, the circling shaft 13 of the motor unit 10 is fixed. The inlet chamber 45 and the operating chamber 46 communicate with each other via the flow path 42 c formed within the vane portion 42 a. A vane guide 47 that guides the movement of the vane portion 42 a is provided between the inlet chamber 45 and the operating chamber 46. The operating chamber 46 communicates with the outside of the casing 53 via an outlet 44. The outlet 44 is provided with an outlet valve 41.

An internal diameter of the operating chamber 46 is set in accordance with a range in which the outer peripheral surface of the rotor portion 42 b is moved by circling of the circling shaft 13.

When the circling shaft 13 circles about the Y axis, the rotor portion 42 b circles about the axial center of the casing 53. Accordingly, the vane portion 42 a oscillates. By the function of the vane portion 42 a, by which the area within the operating chamber 46 is partitioned, the pressure of the operating chamber 46 is changed in accordance with the movement of the circling of the rotor portion 42 b. As a result, the intake of gas into the casing 53 via the inlet 43 and the flow path 42 c and the exhaust of gas from the casing 53 via the outlet 44 are repeated. Since the circling shaft 13 is rotatable about its axis, the circling shaft 13 can rotate about its axis so as to follow the movement of the movable member 42 when the circling shaft 13 circles.

The same effect as that of the fluid machine according to each of the embodiments can be obtained also by the oscillating piston pump 203 according to this embodiment. In particular, a conventional oscillating piston pump has a problem that abraded particles are generated due to sliding between an inner rotor and an outer rotor. However, according to this embodiment, such a problem can be solved.

In FIG. 5, a diameter of the circling shaft 13 is formed to be smaller than that of the rotor portion 42 b. However, those diameters may be substantially the same. Further, it may be possible to provide a structure in which the circling shaft 13 and the rotor portion are formed to be continuous as an integrated member and the vane portion 42 a is provided on the extension of the output end 13 a of the circling shaft 13. Accordingly, the movable member 42 with higher rigidity can be achieved.

(Description on Cam Pump)

FIG. 6 is a view showing a main part of the pump unit 20 according to still another embodiment of the present invention. The pump unit 20 shows a cam pump. The cam pump is also one kind of vane pump.

This cam pump 204 includes a casing 54 that includes an inlet 63, an outlet 64, and an operating chamber 66 communicating with those inlet 63 and outlet 64, and a cylindrical rotor 62 as a movable member arranged within the operating chamber 66. The circling shaft 13 is fixed to the rotor 62. By circling of the rotor 62 within the operating chamber 66, the inlet 63 is opened and closed, and the outlet 64 is opened and closed. A vane 65 that abuts against a side peripheral surface of the rotor 62 by an urging force of a spring 68 is provided within the casing 54. The vane 65 partitions the operating chamber 66 into an intake side and an exhaust side. The outlet 64 is provided with an outlet valve 67.

The same effect as that of the fluid machine according to each of the embodiments can be obtained also by the cam pump 204 according to this embodiment. Further, in the cam pump 204, similar to the oscillating piston pump 203 described above, a diameter of the rotor 62 and that of the circling shaft 13 may be set to be substantially the same in order to increase rigidity.

In the case of using the cam pump 204, the fluid machine may include a rotation regulating mechanism that regulates a rotation of the circling shaft 13 about its axis. As the rotation regulating mechanism, a mechanism including an Oldham ring or a crank pin is used. In the case of using an Oldham ring, the Oldham ring is fixed to an end portion of the circling shaft 13 on the opposite side of the output end 13 a, for example, and is connected to the cover 2 of the casing 5 so as to be movable. The cover 2 is located on the same side of the end portion of the circling shaft 13. In the case of using a crank pin, the crank pin (crank shaft) is rotatably connected between the output end 13 a of the circling shaft 13 and the cover 2 of the casing 5, for example.

Even in the form in which the rotation regulating mechanism is provided to regulate the rotation of the circling shaft 13 about its axis as described above, that is, even in the form to regulate the rotation of the rotor 62 about its axis, operations of the cam pump 204 can be achieved. In this case, however, sliding resistance between the rotor 62 and an inner peripheral surface of the operating chamber 66 is increased.

Second Embodiment

FIG. 7 is a schematic cross-sectional view showing a fluid machine as a drive device according to a second embodiment of the present invention.

In a fluid machine 200 according to this embodiment, the structure of a rotating shaft 106 is different from that of the rotating shaft 6 shown in FIGS. 1 and 2. An end portion (end portion on the opposite side of the output end 13 a of the circling shaft 13) 106 b of the rotating shaft 106 is a closed end. That is, a concave portion 106 a is formed at an eccentric position of the rotating shaft 106, and the circling shaft 13 is rotatably arranged at substantially the center position of the concave portion 106 a.

The same effect as that of the fluid machine according to each of the embodiments can be obtained also by the structure of the motor unit 10 as described above.

Other Embodiments

Embodiments according to the present invention are not limited to the embodiments described above, and other various embodiments are achieved.

The fluid machine according to each of the embodiments can be used also as an internal gear pump or a scroll pump. Here, there are two types of the internal gear pump: one of them is a type in which the position of the rotational center of an internal gear (rotational center about its axis) changes along with operations with respect to the position of the rotational center of an external gear (rotational center about its axis); and the other is a type in which the position of the rotational center of an internal gear is immobile. The structures according to the embodiments of the present invention are applied as the former type.

In the description above, the fluid machine according to this embodiment shows the form to be applied to a pump, but the fluid machine may be applied to a compression machine. Alternatively, any device is applicable without being limited to the fluid machine as long as the device converts the circling movement of the circling shaft into other movements to generate power.

DESCRIPTION OF SYMBOLS

-   6, 106 rotating shaft -   13 circling shaft -   15 bearing -   20 pump unit -   23, 43, 63 inlet -   24, 44, 64 outlet -   27 diaphragm -   28, 38 connecting rod (movable member) -   37 piston head -   42 movable member -   42 a vane portion -   42 b rotor portion -   46, 66 operating chamber -   51 to 54 casing -   62 rotor -   65 vane -   100, 200 fluid machine -   201 diaphragm pump -   202 piston pump -   203 oscillating piston pump -   204 cam pump 

1. A drive device, comprising: a rotating shaft; a circling shaft provided to be eccentric with respect to an axial center of the rotating shaft; and a movable member that is fixed to the circling shaft and generates power by using a circling movement of the circling shaft that circles by a rotation of the rotating shaft.
 2. The drive device according to claim 1, further comprising a bearing that is provided within the rotating shaft and rotatably supports the circling shaft.
 3. The drive device according to claim 2, further comprising a diaphragm mechanism that is driven by the movable member and gives power to a fluid, wherein the movable member is a connecting rod connected to the diaphragm mechanism.
 4. The drive device according to claim 2, further comprising a piston head that is driven by the movable member and gives power to a fluid, wherein the movable member is a piston rod connected to the piston head.
 5. The drive device according to claim 1, further comprising: a casing including an inlet of a fluid, an outlet, and an operating chamber that communicates with the inlet and the outlet and is provided with the movable member therein; and a vane that partitions the operating chamber into an intake side and an exhaust side of the fluid together with the movable member in accordance with a movement of the movable member within the operating chamber.
 6. The drive device according to claim 1, wherein the circling shaft and the movable member are a member formed by integral molding.
 7. The drive device according to claim 2, wherein the circling shaft and the movable member are a member formed by integral molding.
 8. The drive device according to claim 3, wherein the circling shaft and the movable member are a member formed by integral molding.
 9. The drive device according to claim 4, wherein the circling shaft and the movable member are a member formed by integral molding.
 10. The drive device according to claim 5, wherein the circling shaft and the movable member are a member formed by integral molding. 